Mrs. Smith, a 68-year-old woman, lives in a small valley along the coast that is susceptible to the rapid accumulation of air pollutants during temperature inversions inversion An atmospheric condition where a layer of cooler air is trapped near the ground by a layer of warmer air above. When the air cannot rise, pollution at the surface also is trapped and can accumulate, leading to higher concentrations of ozone and particle pollution. . She has a history of a dilated cardiomyopathy and the etiology is unknown. Comprehensive cardiovascular evaluation disclosed no evidence of coronary artery disease or familial history of cardiomyopathy. She has never been a smoker and has no documented parenchymal lung disease, hypertension, diabetes, or drug use. Her history has been characterized by intermittent exacerbations of heart failure with one hospitalization three months ago. Her clinical status is usually defined as New York Heart Association Class II and Stage C. Her medications include a long-acting beta-adrenergic receptor blocker, an ACE inhibitor, spironolactone, and a loop diuretic. She walks outdoors daily as tolerated, weighs herself daily, and adheres to her medication schedule and a low-salt diet.

Over several days, she noted that the air was hazy in association with a temperature inversion. Over the last few days, the air quality for her geographical area has reported an orange level—unhealthy for sensitive groups sensitive groups (also called at-risk populations) A term used for a category of persons at increased risk of experiencing adverse health effects related to air pollution exposures. These groups can be at increased risk due to intrinsic (biological factors), extrinsic (external, non-biological factors), higher exposure, and/or increased dose at a given concentration. The severity of the health effects that these groups experience may be much greater than in the general population.. She has taken precautions to limit her exposure to the smog by reducing her time outdoors and discontinuing her outdoor exercise. Yet she has noted the progressive onset of shortness of breath, a 3-pound weight gain over the last two days, an increase in orthopnea, and leg swelling. She denies paroxysmal dyspnea, palpitations and dizziness, or syncope.

On exam she appears to be volume overloaded with increased central pressures, bibasilar rales, and significant pre-tibial edema. An S3 gallop is present. While her immediate concern is a remedy for her worsening symptoms of heart failure, she asks you whether there is a relationship between the quality of the air and the onset of her symptoms.

Discussion

A recent systematic review and meta-analysis (Shah et al., 2013) shows a relationship between increasing levels of air pollution and hospitalization for heart failure or heart failure mortality. As discussed in other areas of this course, certain clinical conditions such as heart failure and hypertension appear to impart greater vulnerability to some sensitive individuals.  

Heart failure is one of the most relevant and complex health problems facing the U.S. population. According to the National Institute of Health’s National Heart, Lung, and Blood Institute, heart failure is so prevalent in the U.S. population that it should be considered “a new epidemic.” More than 5.8 million Americans are estimated to have heart failure, and about 550,000 new cases of heart failure are diagnosed annually (Roger, 2013). The prevalence of heart failure is expected to grow given the rate at which the U.S. population is aging, the growing prevalence of obesity and diabetes, and the increased percentage of people surviving heart attacks. Education and guidance of this at-risk population appears prudent.

Balanced response

Increasing levels of particle pollution are associated with increasing symptoms of heart failure and hospitalizations for heart failure exacerbation. One cannot link with certainty Ms. Smith's recent exacerbation of heart failure to the environmental stress of the temperature inversion and high concentration of particle pollution. However, there is sufficient evidence to limit exposure to particle pollution in individuals known to be at high risk from the health effects of the pollutant. As a patient with heart failure, Ms. Smith is such an individual. If practical she should limit outdoor exposure by remaining indoors with air conditioning until the air quality improves.  A HEPA air filter HEPA (high-efficiency particulate air) filter A type of pleated mechanical air filter. It is an acronym for "high efficiency particulate air [filter]" (as officially defined by the U.S. Dept. of Energy). This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm). can be effective to lower particle pollution concentrations in the home. Do not recommend an air filtering system that generates ozone (see EPA's guide to air cleaners in the home for more information). While there is limited data showing that filtering the air can modify symptoms associated with air pollution exposure, it is a reasonable recommendation because filtering has been shown to decrease biological and physiological responses to air pollution.